Roller mechanism



Feb. s, 1966 D. J. WRAY 3,233,807

ROLLER MECHANISM Filed June 5, 1964 INVENTOR. .D4/WFL W64/ United StatesPatent O 3,233,807 ROLLER MECHANISM Daniel J. Wray, Jupiter, Fla.,assignor to Radio Corporation of America, a corporation of DelawareFiled June 3, 1964, Ser. No. 372,202 8 Claims. (Cl. 226-180) Thisinvention relates to an improved arrangement for aligning a pressure orpinch roller.

lMagnetic tape which stores binary or video information may be requiredto be driven at relatively high speed. The means employed may include acontinuously rotating capstan over which the magnetic tape passes, and apressure or pinch roller which, when actuated, bears against themagnetic tape and capstan, thereby causing the capstan to drive thetape. To insure that the tape is guided accurately, it is important thatthe surface of the pressure roller be absolutely parallel t the surfaceof the capstan, along the areas of the respective surfaces where theymake Contact.

The object of the present invention is to provide an improved means foraligning a pressure roller with respect to a capstan.

In the arrangement of the invention, the pressure roller, which isengageable with a capstan, is supported by au arm, and this arm ismounted on a shaft which is essentially parallel to the roller. One endof the shaft remains in a relatively fixed position and serves as afulcrum. The other end of the shaft is mounted on a supporting elementwhich may be resiliently mounted along a portion of its peripheralsurface. Means are provided for adjusting the position of the supportingmember, thereby slightly deformng the resilient material. The adjustmentof the position of the supporting member slightly tilts the shaft aboutits fulcrum. This tilting of the shaft is translated by the arm to acorresponding tilting of the pressure roller.

The invention is discussed in greater detail below and is shown in thefollowing drawings, of which:

FIGURE 1 is a plan view of 'the arrangement of the invention; and

FIGURE 2 is a cross-sectional View taken along the line 2-2 of FIGURE 1.

The metal frame shown in the gures supports a shaft 12. The shaft issupported at opposite ends by bearings 14 and 16 which permit the shaftto rotate about its axis through a small angle.

The upper bearing 14 is fixed to a supporting element 18. Acrescent-shaped resilient element which, for example, may be formed ofrubber, is located between the supporting element 18 and the portion 22of the frame 10. The supporting element 18 is formed with ats 24 and 26along the edge portions opposite the resilient element 22 of thesupporting element. These tiats 24 and 26 are preferably substantiallyat right angles to one another.

Adjustment screws 28 and 30 are mountted in the frame 10 and bearagainst the ilats 24 and 26 of the supporting element 18. The purpose ofthese screws is to change the position of the supporting element 18 and,in this way, to adjust the angle of tilt of the shaft 12. This isdiscussed in more detail later.

The shaft 12 supports an arm 32. One end of the arm 32 is formed as ayoke 34a, 34b which supports the axle 36 of a pressure roller 38. Thepressure roller includes an outer surface 40 formed of a resilientmaterial such as rubber, an inner portion 42 which is preferably formedof a metal, and bushings 44 and 46.

The plunger 48 of a solenoid 50 is fixed to the other end 52 of the arm32. The shaft 12 serves as a fulcrum for the arm 32. A spring 54, whichis supported in an 3,233,87 Patented Feb. S, 1966 ICC aperture in theframe 10, serves to bias the arm'- to' the position shown, when thesolenoid 50 is in its unenergized condition. In the position of the armshown, thepressure roller 38 is out of engagement with 'the capstan 56.

In the operation of the pressure roller system shown, when the solenoid50 is actuated, the plunger 48 moves into the solenoid, and the arm 52and shaft 12 rotate through a small angle. This causes the pressureroller 38 to move into engagement with the magnetic tape 58 and capstan56. The capstan, in general, is continuously rotating so that, when thesolenoid is actuated, the pressure roller causes the magnetic tape tobear against the rotating capstan 56 and the tape is driven. Asmentioned in the introduction, it is important that the tape be drivenaccurately. Accuracy is achieved when the pressure roller 38 is exactlyparallel to the capstan 56.

The present arrangement provides means for insuring that the pressureroller is accurately aligned. During the initial assembly of thearrangement above, that is, with the adjustment screws 28 and 30exerting very little pressure against the ats 26 and 24, respectively,the shaft 12 is slightly misaligned in the direction of arrow 60 ofFIGURE 1. Adjustment of screw 28 causes the supporting element 18 tomove. For example, when the screw 28 is turned clockwise, the supportingelement 18 moves against the rubber element 20 slightly compressing therubber. The shaft is mounted in bearings which have a loose internalclearance to permit a slight amount of tilting of the shaft, say througha solid angle of a few degrees, without binding or freezing in thebearing. Therefore, when the screw 28 is adjusted, the supporting member18 moves the upper end 12a of the shaft through an angle in thedirection of arrows 62, the bearing 16 serving as a fulcrum for theshaft. When shaft 12. tilts, the arm 32, which is supported by shaft 12,causes the axle 36 of the drive roller to tilt in the same direction, asindicated by arrows 66 of FIGURE 1.

Adjustment of screw 30 of FIGURE 1 causes the supporting element 18, andalong with it t-he upper end of the shaft 12, to be moved in thedirection of arrow 68 of FIGURE l in a manner similar to that justdescribed. This causes a corresponding movement of axle 36 of thepressure roller and permits alignment of shaft 36 with shaft 64 of thecapstan 56 in the direction 70.

The adjustment of screw 30 is for purposes of reducing skew distortionto the tape. Skew is the tendency of the tape slightly to twist, andsuch motion is undesirabie because it causes slight misalignment of thetracks on the tape with the read-write heads. Adjustment of screw 28controls the amount of crossdrive imparted to the tape. Crossdrive isthe tendency of the one edge of the tape to flutter or ripple as thetape is being driven. KIt is due to the misalignment of the capstan axle64 with the pressure roller axle 36 in the direction of the arrow 66.This misalignment is believed to cause one edge of the tape to travel ata slightly different speed than the other edge of the tape.

The force vector due to the force of the pressure roller against thecapstan and the drag of the magnetic tape is in the direction of theadjustment screws. This makes this supporting element act as if it werea solid member of the frame.

The frame 10 is secured to the supporting structure 81 by means of ashoulder screw 83 which passes through the tail stock 8S. A nut 87 whichis positioned beneath the head of the screw 83 is rotatable about thescrew. The nut is, in reality, an eccentric adjustment which causes theframe to move in the direction of arrows 89 (FIGURE 1) about a pivotpoint 91 located beneath the 3 frame. The pivot point is indicated bythe legended arrow in FIGURE 2 and as a cross in FIGURE l to keep thedrawings simple.

In practice, the pivot includes a shaft (actually a screw) which isfixed to the structure 8l and which passes through a hole in theunderside of the fram-e. The pivot point is behind the shaft 12, asindicated in FIGURE l. Adjustment of the eccentric S7 affects thespacing between the pressure roller and the capstan.

A final adjustment which is possible is that of the set screw 93. Thisscrew bears against the arm 32 and affects the spacing between thesolenoid Si) and its plunger when the relay is in its de-energizedcondition. The screw, accordingly, also affects the spacing between thepressure roller and the capstan when the pressure roller is out ofengagement with the capstan.

What is claimed is:

1. In combination,

a shaft;

rst supporting means for supporting one end portion of the shaft in agiven position;

second supporting means for supporting the opposite end portion of theshaft;

means for adju-sting the position of the second supporting means in adirection substantially perpendicular to the shaft axis and therebyadjusting the position of said opposite end portion of the shaft;

an arm supported by the shaft; and

a pressure roller, the axle of which is supported by said arm in aposition substantially parallel to said shaft.

2. In combination,

a shaft;

first supporting means for rotatably supporting one end portion of theshaft in a given position;

second supporting means for rotatably supporting the opposite endportion of the shaft;

means for adjusting the position of the second supporting means in twosubstantially mutually perpendicular directions which are bothsubstantially perpendicular to the shaft axis and thereby adjusting theposition of said opposite end portion of the shaft;

an arm supported by the shaft; and

a pressure roller, the axle of which is supported by said arm in aposition substantially parallel to said shaft.

3. In combination,

a shaft;

first supporting means for rotatably supporting one end portion of theshaft in a given position;

second snporting means for rotatably supporting the opposite end portionof the shaft;

means for adjusting the position of the second support* ing means in twosubstantially mutually perpendicular directions which are bothsubstantially perpendicular to the shaft axis and thereby adjusting theposition of said opposite end portion of the shaft;

an arm supported by the shaft;

a pressure roller, the axle of which is supported by said arm in aposition substantially parallel to said shaft;

a capstan which is -substantially parallel to the pressure roller and isengageable by the pressure roller; and

means for moving said arm and shaft through an angle such that theroller engages the capstan.

4. In combination,

a frame;

a shaft;

rst supporting means mounted in said frame for supporting one endportion of the shaft in a given position;

second supporting means for supporting the opposite end portion of theshaft, said second supporting means including a member through which theshaft passes, and resilient means located between at least 4. oneperipheral edge portion `of the member and said"`-` frame; adjustingmeans in said frame for exerting pressure against the peripheral edgeportion of said member opposite from the portion thereof at which theresillient means is located, .for moving said second sup-v portingmeans, thereby slightly deforming said resilient means, in a directionsubstantially.perpendicular to the shaft axis, whereby the positionk `ofsaid opposite end portion of said shaft is changed;

an arm supported by the shaft; and

a pressure roller, the axle of which is suppbted by* said `arm .in aposition substantially parallcitosa-id# shaft.

5. In combination',

a frame;

:a shaft; n

first supportingmeans mounted insaid frame for supporting one endportion of the shaft in a given position;

secon-d supporting means forisupporting the opposite end of the shaft,said second supporting means includingI a member through which thenshaft passes, said Imember being formed with mutually perpenf dicularedges along one peripheral portion thereof* :and with a circular edgealong a peripheral portion thereof opposite to said perpendicular edges,and resilient means located between said circular edge portion of themember' and. said'frame;

adjusting screws in said frame, the end-s of which respectively bearagainst said. mutually perpendicular edges for moving said secondsupporting means, thereby slightly deforming said resilient means, inmutually perpendicular directions which are both substantiallyperpendicular to the shaft axis, whereby the position lof said oppositeend portion yof said shaft may be changed;

an arm -supported by the shaft;

-a pressure roller, the axle of which is` supported by said arm in aposition substantially parallel to said, shaft; and

a capstan which is engageable by thepressure roller.

6. In combination,

a frame;

a shaft;

first supporting means mounted in said frame yfor supporting one endportion of the shaft in a given position;

secon-d supporting means for supporting the opposite end portion oftheshaft, said second supporting means including a lmember through which`the shaft passes, said member being formed with mutually perpendicularedges along one peripheral portion thereof and with a circular edgealong` a peripheral portion thereof opposite to said perpendicularedges, and a rubber element shaped to conform to the circular edgeportion of the member and located between said rne'mber and said frame;

adjusting screws in said frame, the ends of which respectively bearagainst said mutually perpendicular edges for moving said secondsupporting means, thereby slightly` `deforming -said rubber element, inmutually perpendicular directions which are both substantiallyperpendicular to the shaft axis, whereby the position |of said `oppositeend portion of said shaft may be changed;

an armv supported by the shaft;

a pressure roller,` the axle of which is supported by said arm in aposition substantially parallel to said shaft; and

a capstan which is engageable by the pressure roller.

'7. In combination,

a shaft;

a supporting frame;

first supporting means in said frame for'rotatably sup porting one endportion of the shaft in a given position;

second supporting means in said frame for rotatably supporting theopposite end portion of the shaft, said second means `comprising asubstantially planar element 4formed with an aperture;

a bushing in which said opposite end portion of the shaft is mounted,located in said aperture and fixed -to said planar element, and acrescent-shaped resilient member located between an edge portion of theplanar element and the frame;

adjusting means for adjusting the position of the second supportingmeans in two substantially mutually perpendicular directions which areboth substantially perpendicular to the shaft `axis and therebyadjusting the position of said opposite end portion of the shaft, saidadjusting means comprising threaded elements mounted in the frame whichbear against edge portions of the planar element opposite the edgeportion thereof at which the resilient member is located;

an arm supported by the shaft;

a pressure roller, the axle of which is supported by said .arm in aposition substantially parallel to said shaft;

a capstan which is substantially parallel to the pressure roller andwhich is engageable by the pressure roller; and

means for moving said arm and shaft through an angle such that theroller engages the capstan.

8. In combination,

a shaft;

a yoke fixed to the shaft;

a pressure roller having an axle which is mounted in the yokesubstantially parallel to the shaft;

first supporting means rotatably supporting one end of the shaft;

second supporting means rotatably support-ing the other end of theshaft; and

means for adjusting the position of the second supporting means in adirection substantially perpendicular to the shaft axis `and therebyadjusting the position of said one end of the shaft.

References Cited by the Examiner UNITED STATES PATENTS 642,141 1/1900Lyon 226--180 X 2,721,650 10/ 1955 Cummings 226-180 X 2,988,257 6/ 1961Lasarev 226-194 X M. HENSON WOOD, IR., Primary Examiner.

1. IN COMBINATION, A SHAFT; FIRST SUPPORTING MEANS FOR SUPPORTING ONEEND PORTION OF THE SHAFT IN A GIVEN POSITION; SECOND SUPPORTING MEANSFOR SUPPORTING THE OPPOSITE END PORTION OF THE SHAFT; MEANS FORADJUSTING THE POSITION OF THE SECOND SUPPORTING MEANS IN A DIRECTIONSUBSTANTIALLY PERPENDICULAR